The invention relates to temperature controlled shipping containers. More specifically, the invention relates to electrical power generation for an air-conditioning system of a temperature controlled shipping container.
Containerized shipment of goods has become a widely accepted means of transporting cargo around the world. Modern containers can be stacked on the decks of ships for shipment overseas. When a container ship arrives at a port, the containers can be efficiently removed from the ship by crane. At the port, the containers can be stacked for further shipment by truck or rail. When the containers are shipped by truck, a single container is usually placed on a semi-trailer chassis. Each rail car generally can support up to four containers.
When the cargo in the container is comprised of perishables such as food stuffs or flowers, the temperature in each of the containers must be controlled to prevent loss of the cargo during shipment. For shipments of perishable goods, specialized containers have been developed which include temperature control units for refrigeration and/or heating. While on board ship, the containers can be connected to a ship's generator to provide power to the temperature control units. When the containers are in port, they may be connected to a power source provided by a local utility.
When, however, the containers are not provided with an external power source, generator sets must be provided to power the temperature control units. For example, when the containers are in transit by railcar, barge, or truck, generator sets may be necessary. Such generator sets usually include a diesel engine to power a generator which in turn provides electric power to the temperature control units. Such generator sets can be clipped directly to a container or fastened to a trailer chassis.
During shipment, the temperature control units and generator sets must operate for extended periods of time. For example, when lettuce is shipped from California to the northeastern United States, the sets may run periodically for several days. During this extended period of time, the temperature control unit and generator set will operate for extended periods of time without inspection by transportation workers. This is particularly true in the case of rail transportation where scores of railcars may, for extended periods of time, be in transport while accompanied by only two or three transportation workers.